Introduction

This note describes what fish protein concentrate is, how it
can be made, and the principal technical problems encountered in making it. The
manufacture and use of fish protein concentrate raise a number of economic and
social questions and these also are briefly discussed in the note.

The term fish protein concentrate is often shortened to FPC,
and this abbreviation is used frequently in this note.

The idea of producing a fish protein concentrate is by no
means new. A vase found in the ruins of Pompeii bore an inscription claiming
that the best liquamen in the world was made in the factories of Umbricus
Agathopus, and liquamen is a kind of FPC. In more recent times the Norwegians
exhibited biscuits containing fish flour at an international exhibition in
1876.

However, it is only in the last twenty-five years that
extensive endeavours have been made to produce fish protein concentrate, and
only in the last few years that most of the technical problems of making FPC on
a large scale have been solved.

What is fish protein
concentrate?

Fish protein concentrate is any stable fish preparation,
intended for human consumption, in which the protein is more concentrated than
in the original fish.

What are the principal types of
FPC?

The Food and Agriculture Organization of the United Nations
defines three types:

Type A:

a virtually odourless and tasteless powder having a maximum
total fat content of 0·75 per cent.

Type B:

a powder having no specific limits as to odour or flavour, but
definitely having a fishy flavour and a maximum fat content of 3 per
cent.

Type C:

normal fish meal produced under satisfactorily hygienic
conditions.

These three types, all of which in a sense resemble fish meal,
are the subject of this note, but there are other fish protein concentrates
which are totally unlike fish meal. These are typically made by hydrolysing fish
protein by means of enzymes or other chemicals and then concentrating the
product into a paste or extract. Hydrolysed products have received much less
technological attention than the variants of fish meal, and they are not
discussed further here.

The fat content is specified when defining types of FPC
because fat when oxidised can produce a strong, often rancid, taste in the
product. The protein content of FPC depends on the raw material used and the
extent to which water has been removed, but the products normally contain at
least 65 per cent protein and, in type A, up to 80 per cent.

How does FPC differ from fish
meal?

Fish meal as produced throughout the world is a very cheap
potential FPC, but it is not intended for human consumption; it is used for
making pig and poultry feeds for farming. Ordinary fish meal is unsuitable for
human consumption for three main reasons:

1. It is not normally made under sufficiently
hygienic conditions to rule out the risk of occasional contamination by
disease-causing bacteria.

2. It usually contains rancid fat which destroys certain
vitamins and may lower the nutritive value of the protein; a fish meal diet
might precipitate vitamin deficiency in poorly nourished people. Moreover the
flavour of the rancid fat is unacceptable in many societies, though not in
all.

3. There is a slight risk that the rancid fat may have a
cumulative toxic effect if consumed over a long period.

The first of these reasons is the most important; thus fish
meal made under hygienic conditions is called FPC type C.

Is FPC the same as fish
flour?

Fish flour is not a precise term, and causes confusion in some
languages, but is the name sometimes given to a product such as FPC type A
which, when ground to a fine powder, can be used as an unobtrusive additive to
prepared foods.

What raw material is used to make
FPC?

The raw material can be fresh fish of almost any kind or size,
or fish meal. The care taken of the fish on the fishing vessel should at least
equal that given to fish for ordinary consumption; it should normally be stored
in ice immediately after capture, and the factory should start processing it
within at the most 48 hours and preferably within 12 hours of landing. Storage
of the raw fish in ice for up to 8 days after capture does not affect the
nutritive value of the FPC.

In some areas of the worlds oceans there are large
stocks of unexploited fish, and these might well be used to make FPC. In any
large-scale operation, FPC would be in direct competition with the fish meal
industry for its raw material. Biologists estimate that the annual world harvest
of marine fish could be doubled or tripled; much of the additional catch would
consist of species not normally eaten but which could be used to make
FPC.

How is FPC made?

The manufacture of types A and B is described here, since type
C is simply hygienically prepared fish meal.

Water and fat together constitute about 80 per cent of the
whole fish, with the fat itself in some species accounting for up to about 20
per cent at times. The manufacture of FPC involves removal of most of the water
and some or all of the fat. Methods developed so far are based mainly on the use
of chemical solvents to remove the water, fat and fishy-tasting components,
either from raw fish or from fish meal. The solvents most successfully used to
make FPC type A are the alcohols, for example ethanol or propanol; ethylene
dichloride is also used. The choice between ethanol and propanol is based on
cost, but since propanol is usually free of excise tax it has tended to replace
ethanol. Normally the solvent is recovered and used again and again.

The manufacturing process is quite complicated, but an outline
of a typical process is shown in the figure. The sequence of operations
is:

1. Fresh whole fish are rinsed with fresh water
soon after landing, weighed and fed to a mincer by conveyor.

2. First extraction: the minced fish are fed to extractor 1
which dehydrates the fish; it is an unheated vessel in which the mince is
agitated for about 50 minutes together with the liquid recovered from extractor
2, which contains some isopropanol.

3. Centrifuging: the contents of extractor 1 are fed to a
continuous centrifuge, where the slurry separates into a solid known as wet
cake, and a liquid. The wet cake is conveyed to extractor 2, and the liquid to a
still for recovery of solvent and fat.

4. Second extraction: extractor 2 is jacketed, and the
temperature is about 75°C. Here the liquid recovered from extractor 3 is
added to the wet cake from extractor 1 and the mixture is agitated for 90
minutes. At the beginning of this stage the cake is almost completely
dehydrated, but has a fat content of about 5 per cent, which is reduced to about
1 per cent during the extraction.

5. Centrifuging: the contents of extractor 2 are centrifuged,
the wet cake is conveyed to extractor 3, and the liquid is returned to extractor
1 for the next batch of raw material.

6. Third extraction: extractor 3 is jacketed, and the
temperature is again about 75°C. Fresh isopropanol is added to the wet cake
and agitated for about 70 minutes. During this stage the fat content is reduced
to about 0·3 per cent.

7. Centrifuging: the contents of extractor 3 are centrifuged
and the wet cake is washed with pure isopropanol for about 50 minutes. The
liquid is returned to extractor 2 for the next batch.

8. Solvent removal: the wet cake is heated in a rotating
vacuum dryer to evaporate the solvent; the vapours are drawn off, condensed and
used again.

9. Grinding and packing: the dried material is conveyed to a
hammer mill, where it is ground to a fine powder and sieved. The FPC is
typically packed in 50-lb fibreboard containers and sent to store ready for
shipment.

The important point to note is that the solid FPC material and
the solvent move through the extractors in opposite directions. Thus the solvent
becomes more contaminated with water and fat as it moves from extractor 3 to
extractor 1, while the FPC loses water and fat as it moves the other way. The
fat can be recovered from the solvent, and the solvent can be used again;
solvent losses are said to be only about 1 per cent of the amount used for a
batch.

What are the remaining technological
problems with FPC?

The problems of manufacture and storage depend on the type of
FPC. For FPC type A, with a low fat content, the main problem is that of flavour
reversion; that is the product may develop a fishy, or fish mealy, flavour
during storage. Complete removal of the solvent is also sometimes difficult with
this product. It is worth noting that the flavour components of the fish are
removed along with the fat, so that the finished product has a bland taste; a
process that removed the fat but left the fresh fish flavour would offer a
considerable advantage, in that the product would be more acceptable to many
consumers.

The main problem with fatty FPC is the prevention of
rancidity; oxidised fat is nutritionally undesirable and frequently unacceptable
because of its flavour.

There have been minor processing problems in the recovery of
both solvent and fat, but these have largely been solved.

Finally it is worth noting that FPC has a somewhat chalky
texture. To remove this characteristic is a rather daunting technical problem,
but there is little doubt that such a change would increase the acceptance of
FPC as a foodstuff

Why is FPC a good protein
source?

First, of course, because it is concentrated; untreated
and unprocessed foods do not generally contain more than about 20 percent
protein, whereas FPC contains about 80 per cent. Secondly, the quality of the
protein is high; by this is meant that the amino acids which make up the protein
are present in just the right balance for human nutrition. Other foods such as
cereals may contain useful amounts of protein but are frequently deficient in
one or more of the amino acids that are essential for growth.

How is FPC used?

Fish protein concentrate type A is an odourless, tasteless
powder which is unattractive to eat by itself; there is therefore a real problem
in finding ways to make most use of it. It has to be incorporated in other foods
such as bread, biscuits, soups and stews at a level that does not affect their
normal properties. Good results have been obtained with macaroni products, a
milk shake drink, spaghetti sauce, infant foods, dietetic foods and breakfast
cereals.

There is less of a problem with other FPC products which have
some flavour. A fishy flavour, even if a rancid one, is acceptable in food in
some societies; thus the FPC can be eaten more or less as it is, or used as a
flavouring in soups or stews.

However, it is true to say that this highly nutritious,
concentrated, stable foodstuff is now available without as yet any clear demands
appearing for its use.

How long does FPC
keep?

Fish protein concentrate is described in its definition as
stable; the term stable here has been tentatively defined as showing no
significant deterioration in 6 months at 27°C when packed in a hermetically
sealed container. Some FPC now being made can certainly reach this standard of
stability.

Is FPC made
commercially?

Although it has been made in Canada, USA, Norway, Sweden,
Morocco, South Africa, Chile, Peru and the UK, FPC is not yet an article of
commerce in the usual sense. Plants capable of producing about 15 tons a day of
FPC type A have recently been completed in the USA, but their output is sold to
the government for use in aid programmes. Since there is no established market,
it cannot yet be claimed that FPC is made commercially. The process, however, is
a commercial one, and not merely experimental.

How much does FPC
cost?

It is difficult to obtain a firm idea of its likely commercial
price; this will depend obviously on the cost of the raw material and the
process used. Estimates vary between 15 and 50 U.S. cents a pound; a commercial
price for type A would probably be close to the latter. These prices compare
very favourably with those for proteins from other sources. Fish protein
concentrate is for example about half the price of non-fat dried milk and about
one-twentieth that of meat for a unit weight of protein.

Will FPC solve the worlds food
problems?

No; neither FPC nor any other protein source will solve the
world food problem unless population growth is slowed. In the short run it is
unlikely that any single source of protein such as FPC will solve such a complex
problem, which in any case is not limited to proteins, although these are
important.

However, F.P.C. could well play a most effective role in
reducing protein deficiency in parts of the world where large sections of the
population suffer from malnutrition. Nutritive studies have shown the remarkable
beneficial effect of adding FPC to the diet; of this there can be no doubt. Its
use is particularly beneficial to growing children and pregnant or nursing
mothers. Twelve grammes, less than half an ounce, of FPC a day will supply the
needed protein to a child; a small FPC plant processing 50 tons of raw fish a
day could provide enough FPC for three quarters of a million children. However,
in some areas of the world where fish are plentiful it may still be more logical
to develop orthodox fish industries to meet shortage of protein, and to confine
FPC to emergency use.

Disregarding for a moment the cost of FPC which, although low,
is not negligible to those most in need of protein, the problem of introducing
FPC to those that need it is more recalcitrant than the problem of making it.
People do not ingest nutrients, they eat food; they will not normally buy and
eat something solely because it is good for them or pay extra for traditional
food simply because it contains a nutritious additive. This social problem of
acceptance is the hardest to deal with; FPC is a completely new product in its
tasteless, odourless form and has none of the traditional attributes of a food.
Many scientists believe that if FPC is introduced first to refugees, orphans and
prisoners it will attract an image of food for the poverty-stricken, which will
increase its rejection on social grounds still further. Ironically, its
introduction as a health food and as concentrated high quality protein to the
wealthier countries is perhaps a more acceptable route for it to reach the
undernourished.

On this kind of question there is endless discussion but,
despite great efforts by UN agencies, individuals and manufacturers, FPC has not
yet found a continuing role in combating malnutrition in any country. In a world
basically short of protein, however, there is little doubt that markets of some
kind will develop for a fish protein concentrate of some kind during the next
decade.